Blood samples were collected to assess eosinophils count. Baseline data are defined as last measurement collected on or prior the date of first dose for Induction Phase.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis.

The Izumo Scale questionnaire assesses the comprehensive 5 different GI symptom domains during the past week and consists with 15 weekly questions (3 questions per 1 domain): Heartburn Symptoms domain(Questions1 through3), Gastric Pain Symptoms domain(Questions4 through6), Stomach Heaviness Symptoms domain(Questions7 through9), Constipation Symptoms domain (Question 10 through12), Diarrhea Symptoms domain (Questions13 through15). Each question is scored on a 6-point Likert scale of "0 = No trouble at all" to "5 = Can't stand it," and the score for each question within a domain is added to determine domain specific scores scaled from 0 to 15, with higher values indicating greater symptom severity.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo).

The Izumo Scale questionnaire assesses the comprehensive 5 different GI symptom domains during the past week and consists with 15 weekly questions (3 questions per 1 domain): Heartburn Symptoms domain(Questions1 through3), Gastric Pain Symptoms domain(Questions4 through6), Stomach Heaviness Symptoms domain(Questions7 through9), Constipation Symptoms domain (Question 10 through12), Diarrhea Symptoms domain (Questions13 through15). Each question is scored on a 6-point Likert scale of "0 = No trouble at all" to "5 = Can't stand it," and the score for each question within a domain is added to determine domain specific scores scaled from 0 to 15, with higher values indicating greater symptom severity. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis.

Clinical response defined as percentage of participants who achieve <4/15 in each of three Symptoms of Interest (Gastric Pain Symptoms domain, Stomach Heaviness Symptoms domain, and Diarrhea Symptoms domain) scores of Izumo Scale from baseline. Histologic response defined as a > 75% reduction of peak gastric and/or duodenal eos count from baseline. Izumo Scale tests 5 different GI symptom domains during past week and consists with 15 weekly questions (3 questions per 1 domain): Heartburn Symptoms domain(Ques1 through3), Gastric Pain Symptoms domain(Questions4 through6), Stomach Heaviness Symptoms domain(Ques7 through9), Constipation Symptoms domain (Question 10 through12), Diarrhea Symptoms domain (Ques13 through15). Each question is scored on a 6-point Likert scale of "0 = No trouble at all" to "5 = Can't stand it," and score for each question within a domain added to determine domain specific scores scaled from 0 to 15, with higher values indicating greater symptom severity.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the subject received IP (CC-93538 or placebo).

Clinical response defined as percentage of participants who achieve <4/15 in each of three Symptoms of Interest (Gastric Pain Symptoms domain, Stomach Heaviness Symptoms domain, and Diarrhea Symptoms domain) scores of Izumo Scale from baseline. Histologic response defined as a > 75% reduction of peak gastric and/or duodenal eos count from baseline. Izumo Scale tests 5 different GI symptom domains during past week and consists with 15 weekly questions (3 questions per 1 domain): Heartburn Symptoms domain(Ques1 through3), Gastric Pain Symptoms domain(Questions4 through6), Stomach Heaviness Symptoms domain(Ques7 through9), Constipation Symptoms domain (Question 10 through12), Diarrhea Symptoms domain (Ques13 through15). Each question is scored on a 6-point Likert scale of "0 = No trouble at all" to "5 = Can't stand it," and score for each question within a domain added to determine domain specific scores scaled from 0 to 15, with higher values indicating greater symptom severity.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the subject received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Blood samples were collected to assess eosinophils count. Baseline data are defined as last measurement collected on or prior the date of first dose for Induction Phase. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo). Only participants with baseline measurements of peak eos analyzed at specified timepoint are included in the analysis.

Blood samples were collected to assess eosinophils count. Baseline data are defined as last measurement collected on or prior the date of first dose for Induction Phase.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis.

Blood samples were collected to assess eosinophils count. Baseline data are defined as last measurement collected on or prior the date of first dose for Induction Phase. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo). Only participants with baseline measurements of peak eos analyzed at specified timepoint are included in the analysis.

Histologic response defined as a > 75% reduction of peak gastric and/or duodenal eos count from baseline.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the subject received IP (CC-93538 or placebo).

Histologic response defined as a > 75% reduction of peak gastric and/or duodenal eos count from baseline. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis.

The Izumo Scale questionnaire assesses the comprehensive 5 different GI symptom domains during the past week and consists with 15 weekly questions (3 questions per 1 domain): Heartburn Symptoms domain(Questions1 through3), Gastric Pain Symptoms domain(Questions4 through6), Stomach Heaviness Symptoms domain(Questions7 through9), Constipation Symptoms domain (Question 10 through12), Diarrhea Symptoms domain (Questions13 through15). Each question is scored on a 6-point Likert scale of "0 = No trouble at all" to "5 = Can't stand it," and the score for each question within a domain is added to determine domain specific scores scaled from 0 to 15, with higher values indicating greater symptom severity. Gastric Pain Symptoms domain, Stomach Heaviness Symptoms domain, and Diarrhea Symptoms domain are Symptoms of Interest.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo).

The Izumo Scale questionnaire assesses the comprehensive 5 different GI symptom domains during the past week and consists with 15 weekly questions (3 questions per 1 domain): Heartburn Symptoms domain(Questions1 through3), Gastric Pain Symptoms domain(Questions4 through6), Stomach Heaviness Symptoms domain(Questions7 through9), Constipation Symptoms domain (Question 10 through12), Diarrhea Symptoms domain (Questions13 through15). Each question is scored on a scale of "0 = No trouble at all" to "5 = Can't stand it," and one symptom domain is scored from 0 to 15, with higher values indicating greater symptom severity. Gastric Pain Symptoms domain, Stomach Heaviness Symptoms domain, and Diarrhea Symptoms domain are Symptoms of Interest. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm. Only participants from ages 12 -19 years old at specified timepoint are included in the analysis.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis.

The EGID Severity Score for participants from 12 to 19 years old assesses 6 different symptoms (vomiting, dysphagia, anorexia, abdominal pain, diarrhea, bloody stool), 2 clinical laboratory tests (albumin, eos ratio of peripheral blood cells) and general condition, including height and weight. The score ranges from 0 to 100 and the higher the score, the greater the severity. A score of ≥ 40 is considered as severe, a score of 15 to 39 as moderate and ≤ 14 score as mild.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the subject received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis. Only participants from ages 12 -19 years old at specified timepoint are included in the analysis.

The EGID Severity Scores are assessed by the investigator. The EGID Severity Score for participants ≥ 20 years old assess the intensity and the frequency of 6 different symptoms (vomiting, dysphagia, anorexia, abdominal pain, diarrhea, bloody stool), 2 clinical laboratory tests (albumin, eos ratio of peripheral blood cells) and 2 medical history items (history of surgery and use of systemic corticosteroid or immunosuppressives). The score ranges from 0 to 82 and the higher the score, the greater the severity. A score of ≥ 40 is considered as severe, a score of 15 to 39 as moderate and a score of ≤ 14 score as mild.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the subject received IP (CC-93538 or placebo). Only participants analyzed at specified at specified timepoint are included in the analysis. Only participants from ages >=20 years years old at specified timepoint are included in the analysis.

The EGID Severity Score for participants from 12 to 19 years old assesses 6 different symptoms (vomiting, dysphagia, anorexia, abdominal pain, diarrhea, bloody stool), 2 clinical laboratory tests (albumin, eos ratio of peripheral blood cells) and general condition, including height and weight. The score ranges from 0 to 100 and the higher the score, the greater the severity. A score of ≥ 40 is considered as severe, a score of 15 to 39 as moderate and ≤ 14 score as mild. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the subject received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis. Only participants from ages 12 -19 years old at specified timepoint are included in the analysis.

The EGID Severity Scores are assessed by the investigator. The EGID Severity Score for participants ≥ 20 years old assess the intensity and the frequency of 6 different symptoms (vomiting, dysphagia, anorexia, abdominal pain, diarrhea, bloody stool), 2 clinical laboratory tests (albumin, eos ratio of peripheral blood cells) and 2 medical history items (history of surgery and use of systemic corticosteroid or immunosuppressives). The score ranges from 0 to 82 and the higher the score, the greater the severity. A score of ≥ 40 is considered as severe, a score of 15 to 39 as moderate and a score of ≤ 14 score as mild. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the subject received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis. Only participants from ages >=20 years old at specified timepoint are included in the analysis.

Any worsening of EGE symptoms during study participation will be documented as an EGE flare. Worsening of EGE symptoms is defined as continuous worsening of symptoms for 2 consecutive visits (4 weeks apart) compared to baseline, measured by the weekly Izumo Scale score (≥ 4 weeks of no change from baseline or ≥ 4 weeks of worsening from baseline).

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the participant received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis.

Any worsening of EGE symptoms during study participation will be documented as an EGE flare. Worsening of EGE symptoms is defined as continuous worsening of symptoms for 2 consecutive visits (4 weeks apart) compared to baseline, measured by the weekly Izumo Scale score (≥ 4 weeks of no change from baseline or ≥ 4 weeks of worsening from baseline). Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the subject received IP (CC-93538 or placebo). Only participants analyzed at specified timepoint are included in the analysis.

Participants who use concomitant corticosteroid at baseline and entered Maintenance Phase

Intent-to-treat (ITT) population which consists of all randomized participants regardless of whether or not the subject received IP (CC-93538 or placebo).

Participants who use concomitant corticosteroid at baseline and entered Maintenance period were included in the analysis.

ITT Population

A treatment emergent adverse event (TEAE) is any AE that emerges during treatment or Safety Follow-up Period having been absent pre-treatment or worsens in severity relative to the pretreatment state. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Safety Population

Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Safety Population

Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Safety Population

Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Safety Population

Blood samples were collected to assess Anti-Drug-Antibody. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Safety Population

Blood samples were collected to assess CC-93538 trough concentrations.

Pharmacokinetic population included all participants who received at least one dose of active drug and have at least one measurable concentration data. Only participants with data available at specified timepoint and receiving CC-93538 were included in the analysis.

Blood samples were collected to assess CC-93538 trough concentrations. Participants that discontinued Induction period without entering maintenance period are included in the CC-93538 360 mg QW arm.

Pharmacokinetic population included all participants who received at least one dose of active drug and have at least one measurable concentration data. Only participants with data available at specified timepoint and receiving CC-93538 were included in the analysis.